Histological & Histochemical Techniques

• Enzymatic Degradation of Catecholamines and COMT Inhibition:
• Catechol-O-Methyltransferase (COMT) catalyzes the transfer of a methyl group from S-adenosylmethionine to a hydroxyl group of catecholamines (dopamine, epinephrine, norepinephrine) and levodopa.
• Entacapone (and Tolcapone) is a selective, reversible COMT inhibitor used in neuropharmacology to prevent peripheral breakdown of levodopa, increasing central dopamine availability.
• Selegiline and Rasagiline are MAO-B inhibitors; Clorgyline is a MAO-A inhibitor.
• nalysis:
• (Entacapone): Correct COMT inhibitor.

Correct option: (3) Entacapone

• Equine Mating Behavior:
• Courtship (vocalizing, nuzzling, flehmen, sniffing the mare's flank) is followed by mounting.
• The actual act of mounting, penile insertion (intromission), pelvic thrusts, and ejaculation in horses is rapid, typically lasting approximately $30 - 40\text{ seconds}$ (about 40 seconds), indicated by rhythmic "tail flagging" in the stallion during ejaculation.
• nalysis:
• (About 40 sec): Correct standard copulatory duration.

Correct option: (1) About 40 sec

• Neonatal Hypothermia Pathophysiology:
• Assertion (A): Hypothermia is a major cause of perinatal mortality in newborn calves, lambs, and piglets. (True).
• Reason (R): Neonates possess an immature, poorly integrated hypothalamic thermoregulatory center, combined with a large surface-area-to-body-mass ratio, wet hair coat at birth, and minimal subcutaneous adipose reserves. They are unable to maintain homeothermic body core temperature in cold ambient environments. (True).
• nalysis:
• Both (A) and (R) are true, and (R) provides the physiological explanation for (A). Hence, Option 1 is correct.